Sumiko had straight hair, which she had tied into two low buns, held up by ribbons. She had a fringe covering her forehead, and she also wore a headband with ribbons, decorated with flowers at each side. She was usually seen wearing goth-lolita clothes.
Sumiko was described to be a kind and cheerful person by Touko, but she was bad when she drank a lot, and she used to sing alone when she drank.
Based on her additions to the Circle's notebook, she was also a philosophical and eccentric girl.
Little of their interaction has been shown, but they seemed to be on good terms and Touko says that she misses the times when they used to sing cheerful songs.
Hika and Sumiko were on good terms. When Touko asked what she wanted from their trip, Hika replied Sumiko. This shows that Hika misses Sumiko dearly and wishes to see her again.
Story EditFallen Crew's notebook, she spots a person whom she doesn't know. Touko explains that the person was Sumiko, a close friend of theirs, who had one day left their group, but doesn't elaborate further.
Some time later, Miki asks Touko what Sumiko was like. Touko replies that she was their close friend who liked to drink often and end up drunkenly singing songs. Saddened by the conversation, Touko tells Miki that she will tell them more about Sumiko some other day.
When Touko asks Hika what she wants from their trip, Hika mentions Sumiko.
- Main article: Category:Sumiko